MacBook Pro freezes when I quit Safari

Occasionally when I quit Safari on my 13" MacBook Pro with retina display, Safari will cause it to completely freeze up. This issue has been going on for a while now but the last time I researched this issue, nobody else had any information on it. I'm wondering if anyone else is having the same problem and wether or not you have found a cause with a solution. I reformatted the drive and did a clean install of OS X El Capitan just a few months ago but it was still happening occasionally. Along with that issue, a new one has been occurring. Safari will sometimes be unresponsive other than refreshing the page. I'll go to click on a website but it won't respond and I don't get any spinning beach ball. If I open a new tab or refresh the page it will become responsive again.